Sorry, Rand, but I'll have to disagree with your mathematical reasoning. Adding new ranking signals does not necessarily diminish the value of links. Let's say theoretically that Google places 50% value on link-based signals and 50% value on non-linked-based signals. Now let's say that Google decides there are a handful of non-link-based signals that they want to implement in the algorithm. They can do so without affecting the emphasis on link-based signals. This would only be necessarily true if Google put equal weight on each individual ranking signal, which I highly doubt that they do.

Hi Jeff, great WBF and I hope to see more YouTube ranking insights on SEOmoz going forward! :)

A few other things that I have noticed about ranking in YouTube:

1) YouTube seems to reward videos for getting a lot of engagement in the first 24 hours, even when you upload it unlisted first. Definitely plan ahead launching your video so that you can get your regulars to watch it as soon as possible. Sometimes you'll notice that fresh videos make their way into competitive SERPs, and I think this has a lot to do with it.

2) Engagement factors are very important, but related to the point above, recency or frequency of engagement seems to carry a lot of weight as well. In other words, if your video has a million lifetime views but none in the last six months, YouTube is likely to favor something fresher. Just like site content, you want to aim for evergreen videos to capture your money keywords.

3) Driving clicks to subscribe, or to watch other videos/playlists via annotations seems to count as a good indication of engagement with your audience. Think of what YouTube wants to reward. They want to reward creators that gain a loyal following who keep coming back to watch more videos, and they want to reward videos that can increase dwell time, which is essentially the statistic they use to impress advertisers and the media.

One question for you (or the other gurus following along). Have you noticed YouTube putting more ranking emphasis on partner channels or monetized videos? I've noticed some of my monetized audioswapped videos get better search visibility than my non-monetized ones, often with similarly optimized videos where the non-monetized one has much better engagement stats.